Many medicament delivery devices are developed for self-administration, i.e. a user performs the medicament delivery her-, or himself. This requires a medicament delivery device which is as safe to use and as easy to handle as possible. In order to meet these requirements, the risk of human errors must be minimized, the number of actions needed to be performed in order to receive a dose need to be reduced and the device must be intuitive and ergonomic to use. Thus, in order to minimize the risk of human errors, it is desirable to have the device as pre-assembled as possible.
Document EP 1349590 B describes an injector having a number of features that facilitate the handling of the injector. The penetration and injection is performed manually by simply pressing the proximal end of a needle shield against the delivery area, causing the shield to move in a distal direction, enabling the needle to penetrate the injection area and thereafter initialize the injection process. When the injection has been completed the injector is withdrawn whereby a needle shield extracts around the needle in a locked way.
Other aspects of injectors are the human aspect of handling the injector regarding how it is held during operation. A general aim is to have the patient holding the injector in an ergonomic way that permits penetration and injection in different locations on the body, such as around the waist and also on the backside of the waist and/or in the buttocks of the patient. Sometimes the patient or the injector do not reach the necessary pressure on the injector, as a result, the administered dose might be inaccurate causing undesired alterations on the patient.
It is considered important for the patient to receive the right dose after the injection has been made, in particular in instances when an injector is used where the patient does not see the injector, e.g. such as around the waist and also on the backside of the waist and/or in the buttocks of the patient.
Additionally, there is a need to simplify the drive mechanism of the medicament delivery device. New ways of creating propelling forces within the device are required in order to assure significant improvements on the weight and handling of the device. Moreover, the disclosure leads to important material savings for the producer, e.g. avoiding the use of several power springs.